Many studies have shown that Bt Cry proteins are highly selective in managing larvae of the target pest species. Bt corn does not affect beneficial insects including honey bees, ladybird beetles, green lacewing larvae, spiders, pirate bugs, damsel bugs, syrphid flies or parasitic wasps. In addition, Bt corn for rootworm control does not affect beneficial soil arthropods including centipedes, millipedes, carrion beetles, tiger beetles, crickets, ants, collembola, or earthworms.
However, indirect effects on natural enemies could occur. Predators, parasites and pathogens of the corn borer or corn rootworm larvae might decline as these pest populations decline. Refuge areas may moderate these indirect effects. Potential declines in beneficial species are predicted to be much less than one would expect if a foliar insecticide were to be used.
On-going research is being conducted to ensure that key beneficial and other non-targets insects are not being affected by Bt corn technology.